Most mechanical and thermal contact assemblies used in the prior art require additional mounting structures, such as rivets, screws, or other hardware, to attach or assemble the protective casing to the heat sink. The use of these additional mounting structures increases the risks of assembly defects and the material cost of manufacturing contact assemblies, as well as the labor cost.
Moreover, some of the prior art contact assemblies require the use of special tools or a high insertion force to attach the protective casing to the heat sink. One known design uses a spring clip to attach the electonic device to the heat sink. However, this clip requires a high insertion force for installment and in addition, the side installation in reorientation of the parts during assembly which increases assembly time.
During assembly, it is also important not to mechanically damage the device or the device leads. Therefore, the goal is to quickly and reliably attach the device to the heat sink with a sufficient force to retain without damaging the device.
The use of addtional components and special mounting tools not only increases the cost of the finished heat sink assembly but also makes field replacement of the protected underlying electronic device difficult and impractical.
When mounting structures such as screws are used there is always a possibility of the screw becoming loose and causing the electronic device to make an insufficient contact with the heat sink for maximum heat transfer. Thus the reliability of prior thermal and mechanical contact assemblies may depend, not only on the casing itself, but also on the mounting hardware used to attach the casing. Since the reliability of any assembly always decreases as the number of parts in the assembly increases, prior art heat sink assemblies which require additional mounting structures are inherently less reliable.